A high-efficiency, low-noise swept blade for wind turbines and an axial flow fan.

Abstract

This utility model belongs to the field of axial flow fan technology, specifically disclosing a high-efficiency, low-noise swept blade for a fan and an axial flow fan. The swept blade includes: a blade body, comprising a suction surface near the air inlet and a pressure surface near the air outlet, with the front and rear ends of the suction and pressure surfaces along the blade's rotation direction being the leading and trailing edges, respectively; a blade stalk, connected to one end of the blade body via a blade root, with the other end of the blade body being the blade tip; wherein the leading edge in the blade tip direction bends forward, and the trailing edge in the blade root direction bends backward, with the suction and pressure surfaces combined to form the swept blade; and a flexible, variable winglet disposed at the blade tip, the height of which varies with the blade deformation. This utility model solves the problem of high aerodynamic noise in existing axial flow fans while improving the working efficiency of axial flow fans.

Description

Technical Field

[0001] This utility model belongs to the field of axial flow fan technology, and in particular relates to a high-efficiency, low-noise swept blade for fans and an axial flow fan. Background Technology

[0002] Axial flow fans are widely used mechanical equipment in industrial and agricultural production and people's daily lives. They cover multiple engineering fields such as power, electricity, chemical, metallurgy and machinery. For example, in the industrial field, they are used for ventilation and air exchange in factory workshops, ventilation and dehumidification in warehouses, and tunnel ventilation; in the construction field, they are used for building ventilation systems and building fire smoke exhaust; and in the agricultural field, they are used for greenhouse ventilation and livestock breeding ventilation.

[0003] With the development of theoretical and experimental research, the advantages of swept blades as propeller and compressor blades in terms of aerodynamic performance and acoustic characteristics have been increasingly confirmed by researchers. A 1984 report from NASA Research Center indicated that aircraft engines using swept propellers reduced fuel consumption by 15%-40% and reduced near-sound field by more than 16 dBA. American Engine Corporation has successfully manufactured aircraft turbines with swept stator and rotor blades, achieving a stage efficiency of 93%. The fact that swept blades have been successfully used in aircraft wing design to reduce drag during transonic and supersonic flight has continuously encouraged researchers to apply this concept to the design of fans and compressors.

[0004] For axial flow fans, aerodynamic noise is the primary noise source, while mechanical noise is significantly lower. The aerodynamic noise of axial flow fans consists of broadband noise distributed across the frequency spectrum and discrete noise from various harmonics. The former is turbulent noise, caused by pressure and velocity fluctuations; the latter is rotational noise, caused by the interference between the moving and stationary blades. Currently, the work done by axial flow fan blades is concentrated at the blade tips. The work done at the blade tips is substantial, and the energy is mainly concentrated at the blade tips, resulting in greater turbulent kinetic energy and relatively higher noise levels. Therefore, designing a high-efficiency, low-noise swept blade has become a key technological challenge. Utility Model Content

[0005] In order to overcome the above-mentioned shortcomings of the prior art, this utility model provides a high-efficiency, low-noise swept blade and axial flow fan for wind turbines, which can solve the above problems.

[0006] To achieve the above objectives, one aspect of this utility model provides a high-efficiency, low-noise swept blade for a wind turbine, comprising:

[0007] The blade includes a suction surface near the air inlet and a pressure surface near the air outlet, with the front and rear ends of the suction surface and pressure surface along the rotation direction of the blade being the leading edge and trailing edge, respectively.

[0008] The petiole is connected to one end of the leaf blade via the leaf root, and the other end of the leaf blade is the leaf tip;

[0009] The leading edge in the direction of the blade tip bends forward, the trailing edge in the direction of the blade root bends backward, and the suction surface and the pressure surface are combined and bent to form a swept blade.

[0010] And a flexible, variable winglet is provided at the blade tip, the height of which varies with the amount of blade deformation.

[0011] Compared with the prior art, this application has the following advantages: by bending the leading edge forward in the direction of the blade tip and bending the trailing edge backward in the direction of the blade root, the suction surface and the pressure surface are combined to form a swept blade. At the same time, a small wing is set at the blade tip according to the size of the blade deformation. The height of the small wing varies with the size of the blade deformation, making the small wing flexible and variable. This solves the problem of high aerodynamic noise in axial flow fans in the prior art, and improves the working efficiency of axial flow fans.

[0012] Furthermore, the angle between the height of the leading edge bend of the blade tip and the trailing edge winglet bend of the blade tip ranges from 1° to 5°.

[0013] Furthermore, the bending curve of the swept blade is a quadratic Bezier curve.

[0014] Furthermore, the blade has an airfoil-shaped cross-section, and the leading edge is designed with rounded corners.

[0015] Furthermore, the pressure surface bends 14.5° towards the suction surface.

[0016] Furthermore, the sweep angle of the leading edge is 70°.

[0017] Furthermore, the thickness of the blade gradually decreases from the leading edge to the trailing edge.

[0018] Furthermore, the trailing edge is provided with serrations.

[0019] Furthermore, the trailing edge also includes a cut that connects to the trailing serration.

[0020] Another aspect of this invention provides an axial flow fan, including an impeller comprising swept blades as described above. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a high-efficiency, low-noise swept blade for a wind turbine according to an embodiment of the present invention.

[0023] Figure 2 for Figure 1 Side view;

[0024] Figure 3 A schematic diagram showing the angle between the leading edge bend and the trailing edge winglet of the blade tip;

[0025] Figure 4 A schematic diagram of the bending structure of the blade towards the suction surface and the coordinates of the bending angle;

[0026] Figure 5 A schematic diagram of the leading edge sweeping bending structure and sweep angle coordinates of a swept blade;

[0027] Figure 6 This is a front view of the impeller;

[0028] Figure 7 for Figure 5 Side view.

[0029] The attached figures are labeled as follows:

[0030] 1. Leaf blade; 2. Leading edge; 3. Petiole; 4. Trailing edge; 5. Serration; 6. Cut; 7. Winglet; 8. Pressure surface; 9. Suction surface; 10. Leaf tip; 11. Leaf root. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] like Figure 1 , Figure 2 As shown, this utility model provides a high-efficiency, low-noise swept blade for wind turbines, comprising:

[0033] The blade 1 includes a suction surface 9 near the air inlet side and a pressure surface 8 near the air outlet side. The front end and rear end of the suction surface 9 and the pressure surface 8 along the rotation direction of the blade 1 are the leading edge 2 and the trailing edge 4, respectively.

[0034] Petiole 3, petiole 3 is connected to one end of leaf body 1 through leaf root 11, and the other end of leaf body 1 is leaf tip 10;

[0035] Among them, the leading edge of the leaf tip 10 bends forward, the trailing edge of the leaf root 11 bends backward, and the suction surface 9 and the pressure surface 8 are combined and bent to form a swept blade.

[0036] And a flexible, variable winglet 7 is provided at the blade tip 10, which varies in height according to the amount of blade deformation.

[0037] Compared with the prior art, this application has the following advantages: the leading edge of the blade tip 10 bends forward and the trailing edge of the blade root 11 bends backward, and the suction surface 9 and the pressure surface 8 are combined and bent to form a swept blade. At the same time, a small wing 7 is set at the blade tip 10 according to the size of the blade deformation. The height of the small wing 7 varies with the size of the blade deformation, so that the small wing 7 is flexible and variable. This solves the problem of high aerodynamic noise in axial flow fans in the prior art, and improves the working efficiency of axial flow fans.

[0038] In this design, a winglet 7 is installed at the blade tip 10, with its height varying according to the degree of blade deformation. This winglet 7's flexibility allows for various performance improvements, which, combined with deformable smart materials, enable the blade profile to adapt to changes in the airflow angle. This allows the blade to operate at the optimal angle of attack while controlling strong adverse pressure separation flow, shock wave structures, and shock wave-boundary layer interference, reducing flow field losses. This results in high efficiency during wind turbine operation, exhibiting a moderately flat characteristic curve, and further improving stability.

[0039] Following the above embodiments, more specifically, as Figure 3 As shown, the angle c between the leading edge bend of the blade tip 10 and the trailing edge winglet 7 of the blade tip 10 ranges from 1° to 5°. Through the above design, the angular difference and height difference between the winglet 7 and the blade tip 10 are limited to achieve the optimal design of the winglet 7.

[0040] Following the above embodiments, more specifically, as Figure 4 and Figure 5As shown, the bending curve of the swept blade is a quadratic Bezier curve. The bending line of either the suction surface 9 or the pressure surface 8, which controls the shape of the blade body 1, can be projected onto the circumferential plane as the blade bending control line. This control allows the establishment of xy-plane rectangular coordinate systems on the circumferential plane, where x and y are the abscissa and ordinate, respectively. Within the xy-plane rectangular coordinate system, the origin is the intersection of the leading or trailing edge of the blade root 11 with the petiole 3, the impeller tangent is used as the abscissa (x), and the blade radial direction is used as the ordinate (y).

[0041] In the xy-plane rectangular coordinate system, the governing equation for the blade bending line is:

[0042] The x-axis coordinate of the blade bending control curve along the suction surface;

[0043] The y-coordinate of the blade along the bending control line of the suction surface;

[0044] The vertical length from the impeller center to the maximum outer diameter of the impeller along the blade height direction;

[0045] The value range of the leading or trailing edge curvature of the bend is 10° to 20°.

[0046] The independent variable of the Bezier function in the bending control line;

[0047] ((1-t) 3 ·a0.x+3·(1-t) 2 ·t·a1.x+3·(1-t)·t 2 ·a2.x+t 3 ·a3.x,(1-t) 3 ·a0.y+3·(1-t) 2 ·t·a1.y+3·(1-t)·t 2 ·a2.y+t 3 ·a3.y)0≤t≤1

[0048] a0 is the origin of the coordinate system, a3 is the end point after the bend, and a1 and a2 are the bend control points;

[0049] Divide the blade into three equal parts along the blade height direction at a0 and a3 along the Y-axis;

[0050] Assuming the total height along the vertical direction of the Y-axis is 10 (100%), then the control parameters of a2 and a3 in the x-direction have a value range of -3 to 3.

[0051] The control parameter in the y-direction has a value range of 1 to 8;

[0052] For a swept blade with a blade length of 321 mm, the three parameters of the control equation for the blade's forward bend control line are:

[0053] The bend angle is 14.5°.

[0054] a0 = 0, 0;

[0055] a1 = 1.5, 3:

[0056] a2 = -2, 10:

[0057] a3 = -3, 10.

[0058] The leading or trailing edge curvature of the blade shape of the controlled sweeping composite blade can be selected and projected into the circumferential plane as the blade sweep control line. The control curve can be established in the circumferential plane as an xy plane rectangular coordinate system, where x and y are the abscissa and ordinate of the xy plane rectangular coordinate system, respectively. In the xy plane rectangular coordinate system, the intersection of the leading or trailing edge of the blade root 11 and the petiole 3 is taken as the origin, the impeller tangent where the blade is located is taken as the abscissa x, and the blade radial direction is taken as the ordinate y.

[0059] In the xy-plane rectangular coordinate system, the governing equation for the blade bending line is:

[0060] x-axis coordinate of blade forward sweep control curve;

[0061] The y-axis coordinate of the blade forward sweep control curve;

[0062] The vertical length from the impeller center to the maximum outer diameter of the impeller along the blade height direction;

[0063] The range of the leading or trailing edge curvature of the sweep angle is 20° to 70°.

[0064] The independent variable of the Bezier function in the bending control line;

[0065] ((1-t) 3 ·b0.x+3·(1-t) 2 ·t·b1.x+3·(1-t)·r 2 ·b3.x+t 3 ·3.x,(1-t) 3 ·b0.y+3·(1-t) 2 ·t·b1.y+3·(1-t)·r 2 ·b2.y+t 3 ·b3.y)0≤t≤1

[0066] b0 is the origin of the coordinate system, b3 is the end point after the sweep angle, and b1 and b2 are the bending control points;

[0067] Divide the blade into three equal parts along the blade height direction at b0 and b2 along the Y-axis;

[0068] Assuming the total height along the vertical direction of the Y-axis is 10 (100%), then the control parameters of b2 and b3 in the x-direction have a value range of -10 to -3.

[0069] The control parameter in the y-direction has a value range of 1 to 8;

[0070] For a swept blade with a blade length of 321 mm, the three parameters of the control equation for the blade sweep control line are:

[0071] Swing angle = 70°;

[0072] b0 = 0, 0;

[0073] b1 = -1, 4;

[0074] b2 = -7, 8;

[0075] b3 = -10, 6.

[0076] Following the above embodiment, more specifically, the blade 1 has an airfoil-shaped cross-section and a rounded leading edge 2, thereby avoiding the sharp blade tip 10 which would reduce the blade's fatigue strength, improving the blade's strength and stiffness, and extending the blade's service life.

[0077] Following the above embodiment, more specifically, the pressure surface 8 is bent 14.5° towards the suction surface 9. In this application, the bent blade's 14.5° bend towards the suction surface 9 can spatially lengthen the blade, increase its work output, and improve its aerodynamic performance and efficiency.

[0078] Continuing with the above embodiment, more specifically, the leading edge 2 has a sweep angle of 70°. Specifically, the 70° sweep angle of the leading edge of the swept blade in this application alters the static pressure distribution at the lower endwall of the blade, reduces the adverse pressure gradient on the suction surface of the blade root 11, weakens the losses caused by the circumferential secondary flow at the endwall of the blade root 11, and causes the low-energy fluid at the blade root 11 to migrate towards the middle of the blade body 1 earlier, reducing the losses and airflow blockage caused by the accumulation of low-energy fluid at the trailing edge of the blade root 11.

[0079] Following the above embodiment, more specifically, the thickness of the blade 1 gradually decreases from the leading edge 2 to the trailing edge 4 to conform to the distribution of stress and deformation of the blade and reduce the risk of breakage.

[0080] Following the above embodiment, more specifically, the trailing edge 4 is provided with serrations 5, wherein the trailing edge 4 also includes a cut 6 connected to the serrations 5. The serrations 5 and the cut 6 improve the aerodynamic performance and efficiency of the blade and reduce noise. It should be noted that the serrations 5 delay the transition from laminar to turbulent flow, reduce surface friction noise, decompose large eddies into small-scale turbulence, and increase the energy decay rate by 3 to 5 times. The cut 6 optimizes the wake structure and reduces pressure pulsation (pressure fluctuations decrease by 20% to 30%).

[0081] Another aspect of this utility model provides an axial flow fan, including an impeller, such as... Figure 6 and Figure 7 As shown, the impeller includes the swept blades as described above. There are five swept blades in the impeller, each of which is mounted on the hub via a stalk 3 to form the impeller.

[0082] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high efficiency low noise swept blade for a fan, characterized in that, include: The blade includes a suction surface near the air inlet and a pressure surface near the air outlet, with the front and rear ends of the suction surface and pressure surface along the rotation direction of the blade being the leading edge and trailing edge, respectively. The petiole is connected to one end of the leaf blade via the leaf root, and the other end of the leaf blade is the leaf tip; The leading edge in the direction of the blade tip bends forward, the trailing edge in the direction of the blade root bends backward, and the suction surface and the pressure surface are combined and bent to form a swept blade. And a flexible, variable winglet is provided at the blade tip, the height of which varies with the amount of blade deformation.

2. A high efficiency low noise swept blade for a fan as claimed in claim 1, wherein, The angle between the height of the leading edge bend of the blade tip and the trailing edge wingtip bend ranges from 1° to 5°.

3. A high efficiency low noise swept blade for a fan as claimed in claim 2, wherein, The bending curve of the swept blade is a quadratic Bezier curve.

4. A high efficiency low noise swept blade for a fan as claimed in claim 3 wherein, The blade has an airfoil-shaped cross-section, and the leading edge is designed with rounded corners.

5. A high efficiency low noise swept blade for a fan as claimed in claim 4 wherein, The pressure surface bends 14.5° towards the suction surface.

6. A high efficiency low noise swept blade for a fan as claimed in claim 5 wherein, The sweep angle of the leading edge is 70°.

7. A high-efficiency, low-noise swept blade for a wind turbine according to any one of claims 1-6, characterized in that, The thickness of the leaf gradually decreases from the leading edge to the trailing edge.

8. A high efficiency low noise swept blade for a fan as claimed in claim 7, wherein, The trailing edge is provided with serrations.

9. A high efficiency low noise swept blade for a fan as claimed in claim 8, wherein, The trailing edge also includes a cut that connects to the serration.

10. An axial flow fan comprising an impeller characterised in that, The impeller includes swept blades as described in any one of claims 1-9.

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